Osteoporosis is a major health issue in postmenopausal women. Our long-term goal is to develop a complementary and alternative medicine (CAM) intervention including dietary supplement (green tea polyphenols, GTP) for bone health. The overall objective of this U01 application is to find an optimal dose of GTP that would be employed to a long-term GTP supplementation clinical trial in postmenopausal osteopenic women. Our central hypothesis is that the GTP will improve bone health through increasing bone formation and decreasing bone resorption. There are 4 different projects involved in the proposed study: Project 1 - bone biomarker measurement in the serum samples; Project 2 -preclinical animal dose-response GTP study; Project 3 - demonstrate BMD measurement proficiency; and Project 4 - human dose-response study of GTP. The significance of this study is in its CAM approach to the mitigation of bone loss in postmenopausal women.